茉莉酸甲酯诱导烟草抗虫的有效浓度和持效期

Effective concentration and period of methyl jasmonate for inducing tobacco resistance to insect pests

为阐明茉莉酸甲酯(Me JA)诱导烟草抗虫机制,用50μmol/L和150μmol/L的Me JA乙醇水溶液喷洒烟苗,24 h和48h后取叶片分别喂食棉铃虫和甜菜夜蛾,每隔6 h监测取食量及体重变化,同时通过Folin-Ciocalteu比色法检测烟叶总多酚含量变化,并利用组织化学染色法统计分泌蔗糖酯的腺毛数。结果显示:(1)对于棉铃虫,50μmol/L和150μmol/L的Me JA喷施烟苗24 h^48 h后,试虫取食量和体重增加量均显著低于对照,而对于甜菜夜蛾,仅150μmol/L Me JA处理烟苗24 h后引起试虫取食量和体重增加量明显降低;(2)Me JA诱导烟叶总多酚含量增加,增加量与Me JA浓度呈正相关;(3)Me JA导致烟叶分泌蔗糖酯的腺毛密度降低,腺毛密度与Me JA浓度呈负相关。Me JA诱导烟草抗虫具有一定的持效期且抗虫效果受其浓度影响,而总多酚含量增加和代谢改变或许是烟草产生抗虫性的部分原因。

To gain insights into the mechanism of tobacco resistance to insect pests induced by methyl jasmonate(Me JA), tobacco plants were sprayed with 50μmol/L and 150μmol/L of Me JA. Tobacco leaves were picked at 24 h and 48 h after tobacco plants were treated with Me JA, and Helicoverpa armigera and Spodoptera exigua were respectively fed with tobacco leaves. The feeding amount and weight gains of H. armigera and S. exigua were determined at an interval of 6h. Subsequently, the effects of various concentration of Me JA on total polyphenol content were determined by folin-ciocalteu colorimetry and glandular hair density of tobacco leaves was investigated by histochemical staining. Results showed that(1) The feeding amount and weight gains of H. armigera significantly decreased compared with controls within 48 h after tobacco plants were sprayed with 50μmol/L Me JA or 150μmol/L Me JA. As for another test insect, S. exigua, only tobacco plants exhibited resistance within 24 h after treatments with 150μmol/L of Me JA.(2) The total polyphenol content of tobacco leaves increased when tobacco plants were sprayed with Me JA, and the increased amount of the total polyphenol content was positively correlated with the applied concentration of Me JA.(3) The glandular hair density of tobacco leaves decreased when tobacco plants were treated with Me JA, and the glandular hair density was negatively correlated with the applied concentration of Me JA. Results indicated that the inducement of Me JA on resistance of tobacco plants to insect pests depended on the concentration and exposure time of Me JA, and that the increase of total polyphenol content and changes of metabolism of tobacco plants might result in insect resistance of tobacco plants induced by Me JA.